code: def test_fix_params():
      mod = RecursiveLS([0, 1, 0, 1], [1, 1, 1, 1])
      with pytest.raises(
          ValueError,
          match=(
              "Linear constraints on coefficients" " should be given"
          ),
      ):
          with mod.fix_params({"const": 0.1}):
              mod.fit()
  
      with pytest.raises(
          ValueError,
          match=(
              "Linear constraints on coefficients" " should be given"
          ),
      ):
          mod.fit_constrained({"const": 0.1})
  
imports: import os
  import numpy
  from numpy.testing import assert_allclose, assert_equal, assert_raises
  import pandas
  import pytest
  from scipy.stats import norm
  from statsmodels.datasets import macrodata
  from statsmodels.genmod.api import GLM
  from statsmodels.regression.linear_model import OLS
  from statsmodels.regression.recursive_ls import RecursiveLS
  from statsmodels.stats.diagnostic import recursive_olsresiduals
  from statsmodels.tools import add_constant
  from statsmodels.tools.eval_measures import aic, bic
  from statsmodels.tools.sm_exceptions import ValueWarning
label_desc: Use image node_id 15 for calling a global function with example usage: test_fix_params() without return types